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Growing Guide: Tomato
Grow and Save Tomato Seeds
Originating in South America, the tomato (Solanum lycopersicum) has the distinction of being one of North America’s favorite garden vegetables. Tomatoes come in hundreds of varieties, from large, ribbed “beefsteak” types to small “cherry” and “pear-shaped” tomatoes and in an array of colors and shapes.
Choosing Tomato Varieties
With over 75 outstanding varieties from Seed Savers Exchange to choose from, determining which tomatoes to grow can be a tough decision! Fortunately, tomatoes can be categorized in several ways to help you narrow down a vast selection to the varieties right for you and your garden.
Four Types of Tomatoes You Need in Your Garden
1. Beefsteak
- Large, meaty, great for burgers and sandwiches
- Our picks: Brandywine (Sudduth’s Strain), Dester
Shop all beefsteak tomato seeds
2. Slicer
- Great for slicing and canning
- Our picks: Cherokee Purple, Green Zebra
3. Cherry
- Great for snacking and salads
- Our picks: Black Cherry, Igleheart Yellow Cherry
4. Paste/Roma
- Great for sauces, salsa, baking, and canning
- Our picks: Amish Paste, Martino’s Roma
Determinate vs. Indeterminate Tomatoes
Tomato plants can be either determinate or indeterminate.
Determinate tomato plants will produce tomatoes that all ripen around the same time.
- Typically small and compact
- Short harvest period
- Ideal for canning
Shop all determinate tomato seeds
Indeterminate tomato plants will continue producing new growth and new fruits until killed by frost
- Typically large and sprawling, need support
- Harvest period of 2-3 months
- Yields usually higher than determinate varieties
- Typically later to mature than determinate varieties
Shop all indeterminate tomato seeds
Tomato Earliness
Different varieties mature at various times in the season, but can generally be categorized into early, mid-season, and late.
Early: <69 days
Our picks: ‘Council Bluffs Heirloom,’ ‘Willie’s Garden,’ ‘Mexico Midget,’ and ‘Baker Family Heirloom’
Mid-Season: 70-84 days
Our picks: ‘Oma’s Orange,’ ‘Chocolate Cherry,’ ‘Italian Heirloom’
Late: 85+ days
Our picks: ‘Peg O’ My Heart,’ ‘Paul Robeson,’ ‘Mortgage Lifter (Halladay’s)’
How to Grow Tomatoes
Tomatoes have a long growing season and are typically started indoors and transplanted into the garden when soil temperatures have sufficiently warmed.
When to Start Indoors
Start tomato seeds indoors 4-6 weeks before the last spring frost. Sow seeds 1/8 inch deep into small containers with sterile potting soil or seed-starting mix. 1.5-2″ cells or 72 plug trays are ideal.
Soil should be moist, but not wet. It should hold its shape when squeezed into a ball, but not drip water.
Learn more about starting seeds.
Time to Germination
Seeds will germinate in 7-14 days when started indoors.
Seedling Care
Tomatoes love bottom heat from heat mats, which can speed up germination. Be sure to remove heat mats after germination occurs to prevent seedlings from growing too rapidly and getting spindly.
Keep seedlings in a well-ventilated space with plenty of sunlight. Keep the soil consistently moist, but not waterlogged. Water when the top layer of soil is dry.
Learn more about nurturing seeds indoors.
Potting Up
Pot up tray-grown seedlings into 3-inch pots when plants have at least two sets of leaves. Potting up is necessary to give seedlings the space and nutrients they need to grow
Learn how to pot up tomato seedlings.
When to Transplant
Once outside temperatures have warmed, gradually harden off tomato transplants by introducing the seedlings to direct sunlight, dry air, and cool nights.
Learn how to harden off seedlings.
Transplant tomato seedlings outdoors on a cloudy day, if possible, as soon as the soil has warmed and after all danger of frost has passed.
Set the plant so the lowest leaves are at the level of the soil. You may even choose to remove the first few sets of leaves and set the tomato plant even deeper.
Add a thick layer of mulch to help suppress weeds, conserve water, and regulate soil temperature.
Learn how to transplant tomato seedlings.
Instructional Videos
Watch this video to learn how to transplant and care for tomatoes.
How to Transplant Tomatoes
Light Requirements
Tomatoes require full sun. Plant your tomatoes in a location with as much sunlight as possible.
Spacing Requirements
Most varieties require ample space to grow, so space your plants 24–48 inches apart in rows at least 36 inches apart.
Plant Care
Watering
Be sure to keep them moist but not waterlogged, and do not allow plants to completely dry out. Tomatoes require about 1 inch of water per week. Water deeply at the base of the plant, avoiding wetting the leaves if possible. Be sure to be consistent—erratic watering causes the fruit to split and encourages blossom end rot.
Weeding
Weed regularly to ensure the plants have room and resources to grow without the competition of weeds.
Hand hoes, collinear hoes, and small scuffle hoes are handy for precision weeding. Be sure to scratch every square inch of soil, even if you don’t see a weed, in order to catch any germinating “thread stage” weeds.
Trellising
Both indeterminate and determinate tomato varieties typically require trellising, staking, or caging to keep the tomato vines off the ground.
Trellising tomatoes has many benefits:
- Promotes airflow and keeps fruits off the soil, preventing disease
- Makes identifying pests and disease easier
- Easier harvesting
- Saves space in the garden
Learn more about building garden trellises.
Pruning
Pruning tomato plants prevents disease, promote airflow, and improves yield by directing plant energy into producing fruit. Using a pair of garden shears, follow these steps to prune tomato plants:
- While the tomato plant is young, pinch off blossoms to promote plant growth
- Always prune any leaves that are touching the ground
- Once the plant begins flowering and setting fruit, prune all stems and leaves beneath the first fruit set
- Pinch suckers to keep tomato plants from getting bushy and out of control
Instructional Video
Watch this video to learn how to trellis and prune tomato plants.
Growing Tomatoes in Containers
With the proper soil, sunlight, and care, tomato plants can thrive in containers. Make sure your container is deep, opaque, and has drainage holes. Use potting soil mixed with a generous amount of compost to add nutrients, increase drainage, and help retain moisture. Smaller varieties—such as ‘Silvery Fir Tree,’ ‘Cream Sausage,’ and ‘Stupice’—are most ideal for container gardening.
Tip: While all tomato types can be grown in containers, determinate tomato plants tend to be more compact.
Learn more about container gardening.
Common Pests
Common tomato garden pests include aphids, spider mites, tomato hornworms, cutworms, stink bugs, whiteflies, flea beetles, thrips, and leafminers.
Monitor tomato plants daily for pests or signs of pest damage. Be sure to check the undersides of leaves. Keep tomatoes well-weeded and pruned. Handpick insects as you see them and place into a bucket of soapy water. A strong blast of water can wash small pests, including eggs and larvae, off leaves. Applying a mixture of neem oil, dish soap, and water to leaves can kill insect eggs, larvae, and aphids.
Tomato pests have natural predators. To help attract these beneficial insects, plant plenty of flowers and native plants.
Common Diseases
Tomatoes are susceptible to a number of diseases, many of which can be mitigated or prevented by trellising and pruning plants. Trellising and pruning help to improve airflow around plants, reducing infections. Rotating crops, removing diseased plants, and watering plants at the base also helps to prevents diseases or curb their spreading, as can mulching the base of the plants.
Blossom end rot: Blossom end rot appears on the blossom end of the fruit (opposite the stem end) and appears as a brown or black flattened or sunken spot. It is caused by a calcium deficiency and typically appears among the first fruits produced by the plant. To prevent blossom end rot, water regularly to keep the soil consistently moist. Any affected fruits should be removed.
Tip: Plant rot-resistant varieties, such as the ‘Wapsipinicon Peach’ tomato.
Early blight: Early blight is a tomato leaf spot disorder that appears as small dark brown spots, often with rings, and yellowing leaves. This soil-borne fungal disease most commonly affects the oldest leaves. Early blight thrives in warm, wet conditions and can cause defoliation and lesions on the stem ends of fruit. To prevent this, water at the base of plants, keeping the leaves dry. Provide good airflow by trellising and pruning plants.
Immediately pinch off any affected leaves, but do not remove any more than a third of the plant’s leaves. If more than a third of the leaves are affected, pull the entire plant.
Late blight: Late blight is another tomato leaf spot disorder that appears as irregularly-shaped brown or black spots on leaves surrounded by a lighter halo. It can also create lesions on fruits. This disease is caused by water mold and can quickly cause the plant to wilt and die. To prevent late blight, water at the base of plants and keep the leaves dry. Provide good airflow by trellising and pruning plants.
If caught early, remove any affected leaves and fruit, but do not remove more than a third of the plants foliage. Do not eat fruits affected by late blight.
Tip: Plant blight-resistant varieties, such as ‘Moonglow’ and ‘Trucker’s Favorite.’
Septoria leaf spot: Septoria leaf spot appears as small, water-soaked, tan or gray spots. These spots continue to enlarge and eventually turn white in the centers. This fungal disease can rapidly defoliate plants, leading to sunscald on fruits. To prevent Septoria leaf spot, water plants at the base and keep the leaves dry. Apply mulch and maintain good airflow.
Remove any diseased leaves, but do not remove more than a third of the plant’s foliage.
Sunscald: Sunscald appears as pale yellow or white spots on the fruit that dry out to a papery texture. This can be caused by over-pruning or pests that destroy tomato leaves. Any affected fruits should be removed.
Tomato mosaic virus: Tomato mosaic virus may stunt plants’ growth and make leaves appear yellow, mottled, bubbly, or curled with spots of dead tissue. Affected fruits may ripen unevenly and look irregular with raised or depressed off-color spots. This virus can be hard to tell apart from other viruses. Tomato mosaic virus can be transmitted by garden tools or through seed. Keep tools sanitized and remove any affected plants immediately to curb the spread of disease.
When and How to Harvest for Food Consumption
Harvest tomatoes when they are firm to the touch but seem to give a little. Ripe fruits will pull easily from the vine. Overripe tomatoes turn deep red with very soft flesh.
Eating
Enjoy tomatoes at peak ripeness sliced into a BLT or mixed together into fresh salsa. In salads, tomatoes are particularly good with mozzarella, basil, olive oil, and seasonings.
If you are lucky to have a bumper crop of tomatoes, try making your own tomato soup, tomato paste, or homemade pasta sauce such as “Sugo: the Juice of Life”, a pasta sauce from Seed Savers Exchange Intern and chef Robin Morgan.
Fried green tomatoes, typically made in the Southern United States, consist of unripe tomatoes coated with cornmeal and fried.
Check out these other tomato recipes:
Storing
Homegrown tomatoes should be used within days of being picked. Store tomatoes at room temperature, away from direct sunlight, with the stem side facing down. Storing tomatoes in the refrigerator may keep tomatoes fresh for a few more days, but can result in flavor loss. If storing tomatoes in the refrigerator, allow them to return to room temperature before use.
Fruits will continue to ripen after being picked if they are stored in a warm place.
You can also dry large tomatoes in the sun or oven. If using an oven, warm to just below 145 degrees F until tomatoes are dried but flexible. Stored in airtight containers in a cool place, they can last up to nine months.
Blanched and cored whole tomatoes can also be frozen or canned.
How to Save Tomato Seeds
Tomatoes make an ideal crop for the beginning seed saver as they are self- pollinating and produce seed the same season as planted. Better yet, you only need a few fruit to get started.
Life Cycle
The tomato is an annual crop. It will complete its full life cycle—including germination, reproduction, and death—in one growing season.
Recommended Isolation Distance
When saving seeds from tomatoes, separate varieties by 10-50 feet.
Other Isolation Methods: Physical Barriers
Tomatoes have perfect flowers, which means each flower contains both pollen-producing (male) and pollen-receiving (female) parts. This means tomatoes are self-pollinating and don’t require insect pollination to produce fruit. Because of this, physical barriers are an effective form of isolation to make sure tomato varieties do not cross. Isolation cages, tents, and other structures can keep tomato varieties separated.
Blossom Bags
Mesh blossom bags, organza bags, or jewelry bags prevent insects from accessing tomato flowers. Tie blossom bags around individual tomato flowers, or clusters of flowers, before they open to keep insects out. Once pollination has occurred, the fruit sets and the flower wilts, and you can remove the bags. Be sure to mark which fruits have been isolated by tying a ribbon around the stem!
Alternatively, you can isolate entire tomato plants by placing a mesh lettuce bag over the entire plant.
Learn more about isolation methods.
Recommended Population Sizes
A single tomato plant can produce viable seed. To maintain a variety over time, save seeds from between 5-10 plants.
Assessing Seed Maturity
Tomato seeds are mature when the fruit is ready to eat.
Cleaning and Processing
Extracting Seeds
There are several methods for extracting tomato seeds.
1. Best for large tomatoes and small quantities of tomatoes:
Slice each fruit in half and squeeze out the pulp and seeds into a container.
2. Best for cherry tomatoes and large quantities:
If you have large quantities of tomatoes or a significant amount of cherry tomatoes, you can also extract seeds by gently stepping on the tomatoes, similar to processing grapes. Keep in mind that this method may require more decanting and rinsing, since none of the fruit material is discarded before the fermentation process.
Fermentation
Leave the container to sit for at least one day in a warm (80-90 degrees F) spot out of direct sunlight so that the pulp can ferment. This process allows the tomato seeds to separate from their gelatinous coating. Plump, viable seed will sink to the bottom of this mixture, and the pulp and lighter, immature seeds will float.
Decanting
When a small amount of mold begins to form on the mixture, add water to the bucket and pour off the floating pulp and immature seeds.
Repeat the decanting process until the water added is clear and only viable seed remains.
Rinsing
After decanting, thoroughly rinse the remaining seeds in running water through a fine mesh strainer. A hose or sink sprayer works great for this step.
Drying
Once thoroughly cleaned, spread seeds in a single layer on a screen, coffee filter, baking tray, etc., to completely dry. Depending on the humidity, this may take 5-7 days. Screens work well to improve airflow around the seeds.
Make sure the seeds are covered or out of reach of critters such as mice. Placing fans in front of the seeds helps to speed along the drying process.
Tomato seeds are dry when they snap or shatter cleanly when crushed. If they bend, squish, or smash, give them more time to dry before storing.
Storage and Viability
When stored in a cool, dry place, tomato seeds will remain viable for 5-10 years.
Learn more about storing seeds.
Instructional Video
Follow along with former greenhouse coordinator Alan as he walks you through the steps of extracting, cleaning, and drying tomato seeds. With a few buckets, a strainer, and a coffee filter, you too can save tomato seeds for future planting!
Tomato Seed Stewardship Stories
Read the stories behind these tomato varieties from SSE’s seed bank collection.
- ‘German Pink’
- ‘Peg O’ My Heart’
- ‘Oma’s Orange’
- ‘Missouri Pink Love Apple’
- ‘Livingston’s Paragon’
- ‘Igleheart Yellow Cherry’
Heirloom Tomatoes Seed Collection
If you’re looking for high-performing heirloom tomatoes to add to your garden, look no further than the Heirloom Tomatoes Seed Collection! Each collection includes six heirloom tomato varieties that deliver unforgettable taste—and good stories, too. Several have also been named champs at our annual Tomato Tasting.
This collection includes one packet of each of the following varieties:
- ‘German Pink’
- ‘Igleheart Yellow Cherry’
- ‘Moonglow’
- ‘Riesentraube’
- ‘Salvaterra’s Select’
- ‘Wisconsin Chief’
Please not that in the event of a seed packet shortage, we will substitute a variety.
Shop the Heirloom Tomatoes Collection here.
More Resources
The New Seed-Starters Handbook, Nancy Bubel
The Seed Garden – The Art & Practice of Seed Saving, Seed Savers Exchange and the Organic Seed Alliance
Seed to Seed, Suzanne Ashworth
Epic Tomatoes, Craig LeHoullier
Ten Tomatoes that Changed the World, William Alexander
Grow the Best Tomatoes, A Storey Country Wisdom Bulletin